ramsies11 Posted February 26, 2013 Share Posted February 26, 2013 hello all, im just talking to make sure ive got this down right, i have a job coming up where the lady has somehow found a big ol' 300 lb gear thats approx. 3' in diamiter. she wants a coffee table made out of the thing. now, if i have this right in my head, make the legs up, weld it with a nickel road and then peen it untill it cools? basically, im welding this cast iron gear to 3 3/4" legs ime making from rd. stock. if i figure this out and can find them, this large gear has 3 holes in it... a little bigger than that of a soda can. she wants me to find more gears (probobaly also gonna be cast iron) and weld them to hold her sodas up, using chains to let em hang. if i do it right, itll look nice, just be expensive. im using a 220V stick welder if that helps any. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 26, 2013 Share Posted February 26, 2013 How good is your insurance if the welds fail and it falls onto something or someone ? Prewelding with nickel is only part of it. I gave up accepting the last few jobs like that I had offfered to me, and I passed them off to a full time welder I know. and I have welded cast before. sounds risky Quote Link to comment Share on other sites More sharing options...
David Gaddis Posted February 26, 2013 Share Posted February 26, 2013 Why not weld a traditional fram for the cast iron wheel to sit on? Then drill and tap for smallish sizr bolts to attach chain etc for the cup holders and additional gears. In the past we always brazed those two metals together when in large dimension...but they must be cooled slowly...like in ashes or dehydrated lime. Brazing a project like this is not for the weak person though. In other configurations I would consider Nickel rods. I never liked them unless they were on a wheel. Carry on Quote Link to comment Share on other sites More sharing options...
Bigred1o1 Posted February 26, 2013 Share Posted February 26, 2013 have you thought about drilling and tapping holes to secure the legs with Quote Link to comment Share on other sites More sharing options...
Larry H Posted February 26, 2013 Share Posted February 26, 2013 Drill 4 1" holes 1" deep in the gear, weld a rod to a plate to your leg. This will give you removable legs that won't fail Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted February 26, 2013 Share Posted February 26, 2013 I bet if you figure another way to secure the table top, other than welding the two metals together, she will love it, especially if you make it look old with some textured bolts, or eye hooks, etc. Good luck. Quote Link to comment Share on other sites More sharing options...
Jim Coke Posted February 26, 2013 Share Posted February 26, 2013 Greetings 11, I think you better Identity the gear first... Old large gears are normally cast steel.. They cast them with for the wear factor and machineability... Plus they must be strong at the tooth contact... It sounds like a risky project to me... If I had to weld on a gear like that I would preheat the whole gear to well above 600 and bring the temp down slow... If you crack it will you be able to find another... I doubt it.. A 300 pound table top is over the top... Nickel welding is like glue. Only on the surface.... Old cast gears are full of grease and carbon.. Good luck on your project Jim Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 26, 2013 Share Posted February 26, 2013 well it depends on how old doesn't it? Casting of steel is a fairly recent thing with most of the early work just pouring an ingot that would then be forged out to deal with the large grain structure casting produced. Most of the large old gear work---stuff over 125 years old is cast iron which is known for it's machinability and "lubricating" qualities. As to the question: I'd agree to go with a mechanical joint first and if not that to braze it---the brass can be a design enhancer. Nickel is an expensive rod to buy and I'd not like a leg to fall off if bumped by a vacuum cleaner! Quote Link to comment Share on other sites More sharing options...
JNewman Posted February 27, 2013 Share Posted February 27, 2013 I have made patterns for gears that were to be cast in steel but I have also made patterns for iron gear blanks. I turned one about a year ago that was over 5' diameter that was being cast in iron. I agree to either build a frame and or bolt it to the legs. With 300 lb I would be going with a much heavier leg than 3/4" round. Any time I am building anything that failure could death injury or property damage. I either want an engineered drawing or I am going to WAY over build it. I would be thinking 1.5" round or square. The other concern is what happens to the floor with 300lb on 3 small legs. Quote Link to comment Share on other sites More sharing options...
Jim Coke Posted February 27, 2013 Share Posted February 27, 2013 Greetings again, 11 Just another thought.... I have my own line shaft shop and have lots of pulleys.. wood and cast.... I would consider using a large wood or cast pulley to set on the floor first and than put put your gear on that.... That would spread the weight per square inch over a large surface... I sure would not want to be the maid that has to dust under that puppy.... Another thought If you cant find a large pulley consider a wood base with lots of surface.. Once again Good Luck Quote Link to comment Share on other sites More sharing options...
Larry H Posted February 27, 2013 Share Posted February 27, 2013 I wasn't saying to make legs out of 3/4 I was saying to use the 3/4 or 1" as locator pins to stop the gear from moving, not that a 300 lb gear will be easy to move, and four legs are in order, Not three. Just my opinion , and you know what that's like. Quote Link to comment Share on other sites More sharing options...
ciladog Posted February 27, 2013 Share Posted February 27, 2013 I wouldn't weld anything to that gear unless you have a way to slowely raise the entire gear up to near 1000 degrees F. If you try to preheat just part of the gear you will probably crack it. Then you would have to cool it very very slowely (lots of thermal blankets). I doubt you have something that can heat a 3' diameter gear so I would take the advice of the others and construct a base to bolt to the gear. Quote Link to comment Share on other sites More sharing options...
JNewman Posted February 27, 2013 Share Posted February 27, 2013 I wasn't saying to make legs out of 3/4 I was saying to use the 3/4 or 1" as locator pins to stop the gear from moving, not that a 300 lb gear will be easy to move, and four legs are in order, Not three. Just my opinion , and you know what that's like. It was the OP who mentioned 3/4" legs. I just checked and a 36" dia disk of steel or iron that is 300lb is just over an inch thick. I think a number of us myself included were thinking thicker. With it that thin Imight rivet the legs on or mortice and tenon them on. One advantage of bolting is it is easier to move the table for installation. Quote Link to comment Share on other sites More sharing options...
Hillbillysmith Posted February 28, 2013 Share Posted February 28, 2013 I'm seriously thinking we need a little more common sense here people... It's a gear, they are SOLID. Regardless if it's cast STEEL or cast IRON, the density of either two is great. As JNewman stated, a 300 pound gear that is 3 FEET in diameter is not all that thick.... I do, however, agree with the rest as i would be opposed to welding such an item. Not because of strength issues, seeing as cast is welded and repaired all the time and put back into service, but because it is being used in a decorative manner. I weld and repair for a living and stick welding is DEFINITELY not a conscientious choice for decoration.... All too often people over-do things (ie; 1.5" rod for the legs on this project for instance) which just drive up the weight and cost. To displace a 300 pound load safely in a residential setting, four legs of a 3/4"-1" diameter will be sufficient, just distribute the load at the floor itself with 4"-6" pads (smaller gears perhaps?? B) ). Use the 3/4"-1" rods to set vertically between the teeth of the gear with a bottom plate on each rod for the gear to set on. Just be sure of the "twist factor once you get the gear set so it doesn't rotate and collapse the legs in that scenario but lets face it, it's a 300 pound gear which will not move all that easily. And, if you're worried about it being top-heavy and tipping over, just ensure that the diameter of which the tips of the legs at the floor set are of a larger diameter than the gear itself by approximately 25% (example; 36" table top [gear] the pattern of the legs at the floor would be 45"-48" diameter)..... Best of luck to you and please post pix for us all to see! -Hillbilly Quote Link to comment Share on other sites More sharing options...
ramsies11 Posted March 30, 2013 Author Share Posted March 30, 2013 welp, in hindsight, not my most intelligent idea. this is why i tell people about my ideas :D, so i can tell if theyre going to go well or fail horribly. really glad i didnt do this project. thank you all for your help. Quote Link to comment Share on other sites More sharing options...
Hillbillysmith Posted April 1, 2013 Share Posted April 1, 2013 What was it that made you decide not to take on the project?? -Hillbilly Quote Link to comment Share on other sites More sharing options...
horseshoe182 Posted April 26, 2013 Share Posted April 26, 2013 i would most probably use 316 stainless rods to weld it. but try and get some heat into it, even if just a little bit. i,ve used stainless rods many times on cast parts with success. i did weld cast leg back onto a old guillotine with full weld prep. it never broke off again. the legs could be designed in such a way that the leg load is spread out , in an effort to reduce stress on each leg. Quote Link to comment Share on other sites More sharing options...
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